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NBC10's Jim Rosenfield gets an inside look at the Vatican gardens, and talks to the group trying to convince Pope Francis to come to Philadelphia for a big gathering next year. (Published Sunday, March 23, 2014)

Updated at 2:37 PM EDT on Monday, Mar 24, 2014

Philadelphia planners who are in Rome ahead of the leadership delegation are telling us now that if the pope comes to Philadelphia next year for the World Meeting of Families (WMOF), the event could be the largest event ever hosted in the city and possibly the continent.

"Some are telling me that it might be the largest global event that will hit North America," said Father Bill Donovan who hails from Havertown, Delaware County.

Donovan has been in Rome for the past few months working diligently as the liaison between the Archdiocese of Philadelphia and the Pontifical Council for Families at the Vatican, which is in charge of the WMOF. The two organizations are collaborating on how the world meeting will unfold in Philadelphia next year from Sept. 22 to 27.

"We're celebrating the family and it will be a great moment in the life of Philadelphia, and the life not only of the church in Philadelphia but of all the great people of Philadelphia," Donovan said.

If the pope does come, he is expected to say mass, which would likely be held along the Ben Franklin Parkway.

"That's our hope," said Bob Ciaruffoli, the president of Philadelphia's World Meeting of Families. "We don't have the final say in it, but that's our obvious choice for all involved. We've been talking about it from almost day one. When you take a look at the amounts of people that are going to be involved, the number of sites are extremely limited."

And the number of people expected in Philadelphia -- if the popular Papa Francesco visits -- keeps growing. On March 7, when Archbishop Chaput announced the members of the delegation team coming to Rome, the number tossed out for people expected to attend a mass by the pope was 1 million. Last Friday, Mayor Nutter told us the number could soar to as many as 2 million.

"I think in recent times at least, there will probably not be another event anywhere near the magnitude of this one, nationally or internationally," Nutter said.

Whatever the number, Fr. Donovan said the World Meeting of Families will be a pivotal time for the pope's intention to keep refocusing efforts around the world, on family.

"The family is really the place where somehow we feel the most loved, most appreciated, most special. So the family is really very important. Since Pope Francis became a pope just a over a year ago, this has been really the hallmark of his rejuvenation. He's really captured the imagination of the world about the importance of the family," Donovan said. "So clearly, this has to be seen as a hallmark of the ministry and the service that he wants to put forth of the church to the world, certainly the family is the keystone of a healthy society."

On a personal level, Fr. Donovan said, working with the Vatican and the Philly Archdiocese on such a big event has been very rewarding.

"And I think I'm particularly joyful about this because being the fifth of eight children, all of my seven brothers and sisters are married with children and so it was a great surprise and a joy to have this type of work which is so dear to my heart because growing up in Havertown, and so many of my friends and family are there and so, it's a particular joy and privilege for me to be involved in this new ministry of the church and new movement of the church."